Wireless systems are moving to higher frequencies in search of more useable bandwidth. There is 2 GHz of spectrum available for communication use at 60 GHz. This is 100 times the carrier bandwidth offered in LTE systems.
Due to the fall-off of received power with increasing frequency of a single antenna element (Friis's Law), millimeter (mm)-Wave communication links use directional antenna gain at both a transmitter and a receiver to achieve a sufficient operational signal-to-noise ratio (SNR).
Antenna gain is achieved by arrays of antenna elements that operate in symphony to create beams of radio-frequency (RF) energy radiating in a particular direction or beam. These beams are formed by coordinating the relative phases of each individual antenna element so that the RF energy constructively interferes in the desired beam direction and destructively interferes elsewhere. The result is a narrow beam of RF energy in a known direction depending on the antenna elements' geometry and phase relationships. The array of antenna elements forms a phased array antenna.